How do you fix the gas guage on a 1988 Ford F-150. It stays on empty all the time.

Yellow with White marking on the wire from the guage to the selector switch. http://ww2.justanswer.com/uploads/sdcrowder/2011-06-10_002304_86_f150_fuel_tank_selsecter_switch_wiring_diagram.gif

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check for a common fuse( Instrument panel)

could be the guage itself, the sending unit for those guages or the wiring in between. find the sending unit, should be two wires the sending unit actually changes the amount of voltage going to the guage. cross the two wires over at the sending unit, the guage should read all the way in one direction, do this for both guages. if the guage moves to an extreme position when the wires are crossed the guage and wiring are fine and the sending unit is the culprit. if you cant get the guages to move by crosing the wires, suspect the guage itself. find you a freindly garage to help w your repair. hope this is useful

the sending unit is out.

im have a similar prob. does your voltage guage work?

my 02 ford f 150 runs with hesitation at idle and gets better when i push the throttle whats going on and im getting no codes?

It is likely that its the sending unit in the tank. One way to determine if its the guage or the sending unit is to ground the wire from the guage and it should peg out. If it doesnt then its the guage if it does then its the sending unit.

need to replace the sending unit

its the float in the tank i have the same problem. it also does it when it gets to 1/4 and could be empty.

i have the same problem and i replaced the shuttle valve and i fixed the problem it is located on the drivers side frame rail just behind the the main high pressure fuel pump it should have 6 lines going into it and out it is a mechanical part so its not repairiable hope this helps